Dance, indie, R&B and pop have all "died" several times over in just the past couple of decades, but no genre seems to be more prone to the sword than hip-hop. It's frequently been declared dead by commentators and even, on occasion, by artists – Nas entitled his 2006 album Hip Hop Is Dead. And last week, on the Guardian's music blog, the critic Simon Reynolds became the latest to call for it to be put out of its misery. He spoke too soon.

The key to hip-hop's vitality in 2009 is not just the fact that great music is being recorded and released, but the sheer breadth of excellence across the genre, and from new and old acts: the year's finest hip-hop album as statement came from much-overlooked veterans DJ Quik & Kurupt, with the no-nonsense, fat-free BlaQKout, but 2009 also offered exciting new faces, with rappers like Gucci Mane, Nicki Minaj and Pill edging closer to mainstream crossover. Indeed, all three have shown how to develop a sustainable career and a fanbase in an era when the music industry is in flux, and when new major label artists are prone to be steered into conservative directions. None has yet released an album in 2009 – Gucci Mane's second, The State vs Radric Davis, is due out next week – but instead they have spent the year honing their craft, fine-tuning their personae and raising their profile, via self-released mixtapes, leaked tracks and guest spots for anyone and everyone. Mixtapes are no longer the preserve of hardcore fans, but a canny promotional tactic to show off skills, build a substantial repertoire and whet the appetite for more material without the pressures attendant on a major label album release.

Gucci Mane and Nicki Minaj are both also indicative of a trend over the past decade away from narrative-based storytelling and towards richly surrealist imagery, wordplay and punchlines; it's prone to derision from fans of hip-hop classicism, but the way they jump between similes and images is thrilling, distinct and endlessly quotable. They treat language like a kid treats a sweet shop, and the fun they have in playing around with it is contagious.

Not, of course, that any one trend is ever the whole story: the other much-hyped emergent name of 2009 was Atlanta's Pill, a determined traditionalist whose gritty, unflinching portrayals of poverty and ghetto life are brought to captivating life by his astonishing capacity for conveying emotion.

At ground level, meanwhile, the jerkin' craze – dismissed as "inane" by Reynolds – took hip-hop back to its street dance roots. With their minimal, rudimentary laptop beats and cut'n'paste samples, the jerk kids are like teenagers entertaining themselves with whatever tools they have at their disposal, and with whatever words spring to mind, in the process bypassing the need for record labels or critical gatekeepers – evidence of popular music moving beyond the music industry. Interestingly, the most impressive stars of the jerk scene are almost all female, from the lipglossed teenage insouciance of The Bangz and Babydollz to the icy sexual contempt of New Era and Pink Dollaz.

None of this is to argue that hip-hop is free of problems. Reynolds is correct to lambast the unfortunate swing towards thumping European club beats in commercial hip-hop (though mistaken to assume that there is a lack of beats as astonishing as any made in his "golden age"). And while marketplace obituaries are probably premature for a genre that boasted 2008's best-selling album in the US – Lil' Wayne's Tha Carter III – hip-hop is no longer the commercial force it was, say, seven years ago, which can lead the casual listener to a false impression of the genre's state.

Hip-hop didn't die when its first golden age came to a close in the early 90s. And it didn't die when the early noughties producers that Reynolds holds up as exemplars ceased making vital work. It takes more to kill the only genre to have colonised all the inhabited continents of the world than one critic not liking the records made in a particular year.